Method and Apparatus for Transmitting and Receiving Downlink Control Information in a Mobile Communication System Supporting Uplink Packet Data Service

1. An apparatus for transmitting uplink packet data in a User Equipment UE of a mobile communication system, the UE including a plurality of hybrid automatic repeat request HARQ processes, comprising: a receiver for receiving a relative grant RG associated with a HARQ process from a Node B; a controller for setting an allowed maximum power ratio in the HARQ process to an allowed maximum power ratio in an immediately previous transmission time interval TTI of the HARQ process, if the RG indicates hold, wherein the RG indicates one of change and hold in the allowed maximum power ratio of a physical channel for transmitting uplink packet data to a reference physical channel; and a transmitter for transmitting packet data based on the set allowed maximum power ratio in the HARQ process to the Node B, wherein if the RG indicates up, the controller increases the latest power ratio used for a previous TTI in the same HARQ process by a predetermined level and sets the increased power ratio as the allowed maximum power ratio of the HARQ process, and wherein if the RG indicates down, the controller decreases the latest power ratio used for a previous TTI in the same HARQ process by a predetermined level and sets the decreased power ratio as the allowed maximum power ratio of the HARQ process.

2. The apparatus of claim 1 , wherein the RG indicates one of change and hold of the allowed maximum power ratio of the HARQ process.

3. The apparatus of claim 1 , wherein the allowed maximum power ratio is equivalent to an allowed maximum data rate of the HARQ process in an uplink transmission.

4. The apparatus of claim 1 , wherein the RG is power ratio control information for uplink transmission and is mapped to +1, 0 or −1 to indicate up, hold or down of the allowed maximum power ratio.

5. An apparatus for transmitting control information for uplink packet data reception for a User Equipment (UE) including a plurality of hybrid automatic repeat request (HARQ) processes, in a Node B of a mobile communication system, comprising: a controller for determining an allowed maximum power ratio in a HARQ process of the UE and setting a relative grant (RG) associated with the HARQ process to hold so that the UE sets the allowed maximum power ratio of the HARQ process to an allowed maximum power ratio of an immediately previous transmission time interval (TTI) of the HARQ process, wherein the RG indicates one of change and hold in the allowed maximum power ratio of a physical channel for transmitting uplink packet data to a reference physical channel; and a transmitter for transmitting the RG to the UE, wherein the controller is adapted to set the RG to up, if the determined allowed maximum power ratio is higher than the latest allowed maximum power ratio in a previous TTI for the same HARQ process, and wherein the controller is further adapted to set the RG to down, if the determined allowed maximum power ratio is lower than the latest allowed maximum power ratio in a previous TTI for the same HARQ process.

6. The apparatus of claim 5 , wherein the RG indicates one of change and hold of the allowed maximum power ratio of the HARQ process.

7. The apparatus of claim 5 , wherein the allowed maximum power ratio is equivalent to an allowed maximum data rate of the HARQ process in an uplink transmission.

8. The apparatus of claim 5 , wherein the RG is power ratio control information for uplink transmission and is mapped to +1, 0 or −1 to indicate up, hold or down of the allowed maximum power ratio.

9. A method for transmitting control information for uplink packet data reception for a User Equipment (UE) including a plurality of hybrid automatic repeat request (HARQ) processes, in a Node B of a mobile communication system, comprising: determining an allowed maximum power ratio in a HARQ process of the UE and setting a relative grant (RG) associated with the HARQ process to hold so that the UE sets the allowed maximum power ratio of the HARQ process to an allowed maximum power ratio of an immediately previous transmission time interval (TTI) of the HARQ process, wherein the RG indicates one of change and hold in the allowed maximum power ratio of a physical channel for transmitting uplink packet data to a reference physical channel; and transmitting the RG to the UE, setting the RG to up, if the determined allowed maximum power ratio is higher than the latest allowed maximum power ratio in a previous TTI for the same HARQ process; and setting the RG to down, if the determined allowed maximum power ratio is lower than the latest allowed maximum power ratio in a previous TTI for the same HARQ process.

10. The method of claim 9 , wherein the RG indicates one of change and hold of the allowed maximum power ratio of the HARQ process.

11. The method of claim 9 , wherein the allowed maximum power ratio is equivalent to an allowed maximum data rate of the HARQ process in an uplink transmission.

12. The method of claim 9 , wherein the RG is power ratio control information for uplink transmission and is mapped to +1, 0 or −1 to indicate up, hold or down of the allowed maximum power ratio.

13. A method for transmitting uplink packet data in a User Equipment (UE) of a mobile communication system, the UE including a plurality of hybrid automatic repeat request (HARQ) processes, comprising: receiving a relative grant (RG) associated with a HARQ process from a Node B; setting an allowed maximum power ratio in the HARQ process to an allowed maximum power ratio in an immediately previous transmission time interval (TTI) of the HARQ process, if the RG indicates hold, wherein the RG indicates one of change and hold in the allowed maximum power ratio of a physical channel for transmitting uplink packet data to a reference physical channel; and transmitting packet data based on the set allowed maximum power ratio in the HARQ process to the Node B, increasing the latest power ratio used for a previous TTI in the same HARQ process by a predetermined level and setting the increased power ratio as the allowed maximum power ratio of the HARQ process, if the RG indicates up; and decreasing the latest power ratio used for a previous TTI in the same HARQ process by a predetermined level and setting the decreased power ratio as the allowed maximum power ratio of the HARQ process, if the RG indicates down.

14. The method of claim 13 , wherein the RG indicates one of change and hold of the allowed maximum power ratio of the HARQ process.

15. The method of claim 13 , wherein the allowed maximum power ratio is equivalent to an allowed maximum data rate of the HARQ process in an uplink transmission.

16. The method of claim 13 , wherein the RG is power ratio control information for uplink transmission and is mapped to +1, 0 or −1 to indicate up, hold or down of the allowed maximum power ratio.